MANAGING UREA-CONTAINING FERTILIZERS

Larry G. BundyLarry G. Bundy

Department of Soil ScienceDepartment of Soil Science

University of WisconsinUniversity of Wisconsin

OVERCOMING NITROGEN VOLATILIZATION LOSSES

Larry G. BundyLarry G. Bundy

Department of Soil ScienceDepartment of Soil Science

University of WisconsinUniversity of Wisconsin

Nitrogen Fertilizer Use in Wisconsin, 1984 and 2000.

Tons of N (1000’s)Tons of N (1000’s) % of N use% of N use

N sourceN source 19841984 20002000 19841984 20002000

NHNH33 7575 4141 4444 2525

UreaUrea 4545 6363 2727 3838

UANUAN 5050 6161 2929 3737

TotalTotal 170170 165165

N fertilizer use in Wisconsin (tons of materials)

30

40

50

60

70

80

90

100

110

1995 1996 1997 1998 1999 2000

To

ns

of

N (

10

00

's)

Anhydrous Ammonia

Nitrogen Solutions

Urea

Reactions of urea in soil

(NH(NH22))22CO + 2HCO + 2H2200Urea WaterUrea Water

Equation 1.Equation 1.

Urea HydrolysisUrea HydrolysisSoil

Urease(NH(NH44))22COCO33

Ammonium CarbonateAmmonium Carbonate

Equation 2.Equation 2.

(NH(NH44))22COCO33 + 2H + 2H++ 2NH 2NH4 4 + CO+ CO22 + H + H2200Ammonium Ammonium Carbon WaterAmmonium Ammonium Carbon WaterCarbonate Dioxide (gas)Carbonate Dioxide (gas)

+

Equation 3.Equation 3.

NHNH44 + OH + OH- - NHNH33 + H + H22OOAmmonium Hydroxyl Ammonia WaterAmmonium Hydroxyl Ammonia Water

+

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4

Ure

a h

ydro

lyze

d (

%)

79o

62o

50o

Time after urea application (days)

Rates of urea hydrolysis in a silt loam soil at three temperatures

Change in soil pH in a urea-treated silt loam at two temperatures

Time after urea application (days)

50o

79o

Soil pH effects on percentages of N present as ammonia and ammonium

Ammoniacal NAmmoniacal N

Soil pHSoil pH AmmoniaAmmonia AmmoniumAmmonium

---------------% -----------------------------% --------------

66 0.0580.058 99.9499.94

77 0.570.57 99.4399.43

88 5.45.4 94.694.6

99 36.536.5 63.563.5

Ammonia Volatilization Losses

Urea and urea-containing fertilizers Urea and urea-containing fertilizers Surface applications onlySurface applications only Tillage or rain in 2-3 days controls Tillage or rain in 2-3 days controls

lossloss Large losses are rareLarge losses are rare Maximum loss = 20-30 % of NMaximum loss = 20-30 % of N

Factors Favoring Ammonia Loss

No rain or irrigation after applicationNo rain or irrigation after application Crop residue on the soil surfaceCrop residue on the soil surface High temperaturesHigh temperatures High soil pHHigh soil pH Low clay & organic matter (low CEC) Low clay & organic matter (low CEC) Initially moist soil followed by dryingInitially moist soil followed by drying

Extent of Extent of AmmoniaAmmonia

Volatilization LossesVolatilization Losses

Effect of ammonia loss from surface-applied fertilizers on corn yield, Lancaster, WI

N sourceN source Ammonia lossAmmonia loss

(%)(%)

YieldYield

(bu/acre)(bu/acre)

NoneNone ---- 8383

UreaUrea 1616 122122

UAN solution UAN solution (28%)(28%)

1212 125125

AmmoniumAmmonium

nitratenitrate

22 132132

Oberle & Bundy, 1988. Data from one of four experiments.Oberle & Bundy, 1988. Data from one of four experiments.

Effect of ammonia loss from surface-applied fertilizers on grass pasture yield, Lancaster,

WIN sourceN source Ammonia lossAmmonia loss

(%)(%)

YieldYield

(tons/acre)(tons/acre)

NoneNone ---- 0.740.74

UreaUrea 1919 1.091.09

AmmoniumAmmonium

nitratenitrate

11 1.301.30

Oberle & Bundy, 1988. N rate = 60 lb N/acre.Oberle & Bundy, 1988. N rate = 60 lb N/acre.

Nitrogen Source and Management Comparisons

Nitrogen Source Comparisons Nitrogen Source Comparisons in No-till Cornin No-till Corn

Nitrogen source and placement effects on no-till corn yield and ear leaf N

concentration1

TreatmentTreatment YieldYield Ear leaf NEar leaf N

bu/acrebu/acre %%

Ammonia, inj.Ammonia, inj. 138138 3.063.06

UAN injectedUAN injected 135135 2.852.85

UAN surfaceUAN surface 118118 2.482.48

Urea surfaceUrea surface 123123 2.572.57

11 Ave.of seven expts. Mengel et al., 1982 (Indiana)Ave.of seven expts. Mengel et al., 1982 (Indiana)

Effect of N source and application method on corn yield, Janesville and

Winnebago, WI1

YieldYield

Application methodApplication method WinnebagoWinnebago JanesvilleJanesville

-------- bu/acre ---------------- bu/acre --------

UAN surface broadcastUAN surface broadcast 163163 146146

UAN surface bandUAN surface band 153153 139139

Anhydrous ammoniaAnhydrous ammonia 165165 146146

11 Bundy et al., 1992. Yields are means of 3 yr, 2 N rates, and 4 tillagesBundy et al., 1992. Yields are means of 3 yr, 2 N rates, and 4 tillages

Effect of N source & application method on corn yield, Arlington, WI1

YearYear

N source & methodN source & method 19931993 19941994 19951995

----------- bu/acre -------------------- bu/acre ---------

Ammonium nitrateAmmonium nitrate 118 a118 a 177 a177 a 163 a163 a

UAN sprayUAN spray 94 bc94 bc 140 b140 b 152 a152 a

UAN spray + rainUAN spray + rain 105 ab105 ab 139 b139 b 159 a159 a

UAN sprinkleUAN sprinkle 86 bc86 bc 148 b148 b ----

UAN injectedUAN injected ---- ---- 157 a157 a

Urea Urea 83 c83 c 155 b155 b 160 a160 a1 1 Bundy & Andraski, 1997, Rain = 0.5 inchBundy & Andraski, 1997, Rain = 0.5 inch

Treatments in Nitrogen-Residue Decomposition Study

Times and rates of N (UAN and Times and rates of N (UAN and ammonium sulfate)ammonium sulfate)

Sulfur as gypsum applied to Sulfur as gypsum applied to equalize sulfur equalize sulfur

Treatments applied to residue of Treatments applied to residue of previous corn crop. previous corn crop.

Nylon mesh bag for residue quantity & composition measurements

Nitrogen timing, source, & rate effects on corn grain yield, Arlington, 1999-2001

N timing & rate (lb N/acre)N timing & rate (lb N/acre) Yield 1999Yield 1999 Yield 2000Yield 2000 Yield 2001Yield 2001

FallFall SpringSpring ---------------- bu/acre ------------------------------- bu/acre ---------------

00 00 167 b167 b 63 e63 e 105 e105 e

30 UAN30 UAN 160 UAN160 UAN 219 a219 a 146 abc146 abc 191 b191 b

30 AS30 AS 160 AS160 AS 220 a220 a 158 a158 a 202 ab202 ab

00 190 UAN190 UAN 219 a219 a 148 ab148 ab 194 b194 b

00 190 AS190 AS 216 a216 a 160 a160 a 208 a208 a

100 AS100 AS 90 UAN90 UAN 220 a220 a 136 bc136 bc 207 a207 a

Nitrogen Source and Management Comparisons

Urease Inhibitors to Control Urease Inhibitors to Control Ammonia LossAmmonia Loss

Urease Inhibitor

N-(n-butyl) thiophosphoric N-(n-butyl) thiophosphoric triamide (NBPT)triamide (NBPT)

Commercial product - Commercial product - AgrotainAgrotain

Grain yield increase from use of a urease inhibitor with urea-containing fertilizers

Experimental Experimental sitessites

No.of No.of

sitessites

Yield increaseYield increase

Urea UANUrea UAN

------- bu/acre ------------- bu/acre ------

All sitesAll sites 7878 4.34.3 1.61.6

N responsiveN responsive 6464 5.05.0 2.82.8

SignificantSignificant

NHNH3 3 lossloss

5959 6.66.6 2.72.7

11// Hendrickson, 1992Hendrickson, 1992

Nitrogen Source and Management Comparisons

Winter Applications of UreaWinter Applications of Urea

Effect of nitrogen source, time, and rate on corn yield, Illinois1

Nitrogen treatmentNitrogen treatment Nitrogen rateNitrogen rate

Source/methodSource/method TimeTime 00 120120 180180 240240

------- Yield (bu/acre) -------------- Yield (bu/acre) -------

None (control)None (control) 8989

Urea/surfaceUrea/surface WinterWinter 9494 123123 126126

Urea/Incorp.Urea/Incorp. SpringSpring 140140 157157 165165

Anhydrous Anhydrous ammoniaammonia

SpringSpring 149149 157157 158158

1 1 Illinois Agronomy Handbook, 2001-2002.Illinois Agronomy Handbook, 2001-2002.

Nitrogen Source and Management Comparisons

Preplant Urea ApplicationsPreplant Urea Applications

on Sandy Soilson Sandy Soils

Effect of N source and timing on corn yield, Hancock, WI (2-yr ave.)

PreplantPreplant

N rateN rate InhibitorInhibitor UreaUrea NHNH33

lb/acrelb/acre --------- bu/acre ------------------ bu/acre ---------

00 3535

7070 -- 6161 8787

++ 8080 9999

140140 -- 101101 124124

++ 109109 134134

210210 -- 9898 142142

++ 119119 137137

Effect of N source and timing on corn yield, Hancock, WI (2-yr ave.)

SidedressSidedress

N rateN rate InhibitorInhibitor UreaUrea NHNH33

lb/acrelb/acre --------- bu/acre ------------------ bu/acre ---------

00 3535

7070 -- 9999 8989

++ 106106 104104

140140 -- 127127 127127

++ 129129 125125

210210 -- 135135 137137

++ 142142 133133

Summary Urea-containing fertilizers are widely Urea-containing fertilizers are widely

used (75-80% of the N in Wisconsin).used (75-80% of the N in Wisconsin). Ammonia loss can occur from surface Ammonia loss can occur from surface

applied urea fertilizersapplied urea fertilizers Soil and climate factors influence Soil and climate factors influence

ammonia loss.ammonia loss. Maximum losses seldom exceed 20% of Maximum losses seldom exceed 20% of

applied N.applied N.

Summary N source comparisons sometimes show N source comparisons sometimes show

better performance with non-urea materials better performance with non-urea materials Factors other than ammonia loss may Factors other than ammonia loss may

contribute to these results.contribute to these results. Urease inhibitors can reduce ammonia loss Urease inhibitors can reduce ammonia loss

from urea fertilizers.from urea fertilizers. Economic benefits from inhibitors is Economic benefits from inhibitors is

uncertain.uncertain.

Summary

Winter applications of urea on Winter applications of urea on frozen soils subject to N lossesfrozen soils subject to N losses

Preplant applications of urea on Preplant applications of urea on sandy soils should be avoidedsandy soils should be avoided

Controlling Nitrogen Volatilization Losses

Incorporate or inject urea-Incorporate or inject urea-containing fertilizerscontaining fertilizers

Use non-urea N sources for surface Use non-urea N sources for surface applications applications

Consider a urease inhibitor where Consider a urease inhibitor where risk of volatile loss is highrisk of volatile loss is high

Corn Yield with surface applied N sources, Lancaster, WI

83

122 125132

0

20

40

60

80

100

120

140

Yie

ld (

bu/a

cre)

None Urea UAN Am Nitrate

Effect of N source and timing on corn yield, Hancock, WI

PreplantPreplant SidedressSidedress

N rateN rate InhibitorInhibitor UreaUrea NHNH33 UreaUrea NHNH33

lb/acrelb/acre -------------- bu/acre --------------------------- bu/acre -------------

00 3535

7070 -- 6161 8787 9999 8989

++ 8080 9999 106106 104104

140140 -- 101101 124124 127127 127127

++ 109109 134134 129129 125125

210210 -- 9898 142142 135135 137137

++ 119119 137137 142142 133133